Faculty Bibliography

BACKGROUND:Patients undergoing total knee arthroplasty (TKA) are at increased risk of venous thromboembolism (VTE). Aspirin has been shown to be effective at reducing rates of VTE. In select patients, more potent thromboprophylaxis is indicated, which has been associated with increased rates of bleeding and wound complications. This study aimed to evaluate the effect of thromboprophylaxis choice on rates of early prosthetic joint infection (PJI) following TKA. METHODS:A review of 11,547 primary TKA patients from 2013 to 2019 at a single academic orthopaedic hospital was conducted. The primary outcome measure was PJI within 90 days of surgery as measured by Musculoskeletal Infection Society criteria. There were 59 (0.5%) patients diagnosed with early PJI. Chi-square and Welch-Two Sample t-tests were used to determine statistically significant relationships between thromboprophylaxis and demographic variables. Significance was set at p<0.05. Multivariate logistic regression adjusted for age, body mass index, sex, and Charlson comorbidity index was performed to identify and control for independent risk factors for early PJI. RESULTS:There was a statistically significant difference in the rates of early PJI between the aspirin and non-aspirin group (0.3 vs 0.8%, p<0.001). Multivariate logistic regressions revealed that patients given aspirin thromboprophylaxis had significantly lower odds of PJI (odds ratios (OR)=0.51, 95% Confidence Interval (CI) 0.29 to 0.89, p=0.019) compared to non-aspirin patients. CONCLUSIONS:The use of aspirin thromboprophylaxis following primary TKA is independently associated with a lower rate of early PJIs. Arthroplasty surgeons should consider aspirin as the gold standard thromboprophylaxis in all patients in which it is deemed medically appropriate and should carefully weigh the morbidity of PJI in patients when non-aspirin thromboprophylaxis is considered.

PURPOSE/OBJECTIVE:The previous literature suggests that 25-30% of patients who undergo total knee arthroplasty (TKA) are using opioids prior to their surgery. This study aims to investigate the effect of preoperative opioid use on clinical outcomes and patient-reported outcome measures (PROMs) following TKA. METHODS:We retrospectively reviewed 329 patients who underwent primary TKA from 2019 to 2020, answered the preoperative opioid survey, and had available PROMs. Patients were stratified into two groups based on whether they were taking opioids preoperatively or not: 26 patients with preoperative opioid use (8%) and 303 patients without preoperative opioid use (92%) were identified. Demographics, clinical data, and PROMs [Forgotten Joint Score (FJS-12), Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS, JR), and Veterans RAND-12 Physical and Mental components (VR-12 PCS and MCS)] were collected. Demographic differences were assessed with Chi-square and independent sample t-tests. Outcomes were compared using multilinear regression analysis, controlling for demographic differences. RESULTS:Preoperative opioid users had a significantly longer length-of-stay (2.74 vs. 2.10; p = 0.010), surgical time (124.65 vs. 105.69; p < 0.001), and were more likely to be African-American (38.5 vs. 14.2%; p = 0.010) compared to preoperative opioid-naive patients. Postoperative FJS-12 did not statistically differ between the two groups. While preoperative KOOS, JR scores were significantly lower for preoperative opioid users (41.10 vs. 46.63; p = 0.043), they did not significantly differ postoperatively. Preoperative VR-12 PCS did not statistically differ between the groups; however, both 3-month (33.87 vs. 38.41; p = 0.049) and 1-year (36.01 vs. 44.73; p = 0.043) scores were significantly lower for preoperative opioid users. Preoperative VR-12 MCS was significantly lower for preoperative opioid users (46.06 vs. 51.06; p = 0.049), though not statistically different postoperatively. CONCLUSION/CONCLUSIONS:At 8%, our study population had a lower percentage of opioid users than previously reported in the literature. Preoperative opioid users had longer operative times and length of stay compared to preoperatively opioid-naive patients. While both cohorts achieved similar clinical benefits following TKA, preoperative opioid users reported lower postoperative scores with respect to VR-12 PCS scores. LEVEL III EVIDENCE/METHODS:Retrospective Cohort.

INTRODUCTION/BACKGROUND:Stiffness and decreased range of motion frequently lead to hindrance of activities of daily living and dissatisfaction follow total knee arthroplasty (TKA). This study aims to evaluate the effect of non-aspirin (ASA) chemoprophylaxis and determine patient-related risk factors for stiffness and need for manipulation under anesthesia (MUA) following primary TKA. MATERIALS AND METHODS/METHODS:A review of all patients undergoing primary TKA from 2013 to 2019 at a single academic orthopedic hospital was conducted. The primary outcome measure was MUA performed post-operatively. Chi-square analysis and Mann-Whitney U test were used to determine statistically significant relationships between risk factors and outcomes. Significance was set at p < 0.05. Univariate logistic regression was performed to control for identified independent risk factors for MUA. RESULTS:A total of 11,550 patients undergoing primary TKA from January 2013 to September 2019 at an academic medical center were included in the study. Increasing age and Charlson Comorbidity Index were associated with statistically significant decreased odds of MUA (0.93, 95% CI: 0.92-0.94, p < 0.001, OR 0.71, 95% CI 0.63-0.79, p < 0.001). Active smokers had a 2.01 increased odds of MUA (OR 2.01, 95% CI 1.28, 3.02, p < 0.001). There was no significant difference in rates of MUA between ASA and non-ASA VTE prophylaxis (p 0.108). CONCLUSIONS:Younger age, lower CCI, and history of smoking are associated with a higher rate, while different chemical VTE prophylaxis does not influence rate of MUA after TKA. Arthroplasty surgeons should consider these risk factors when counseling patient preoperatively. Understanding each patients' risk for MUA allows surgeons to appropriately set preoperative expectations and reasonable outcome goals.

BACKGROUND:As greater emphasis is being placed on opioid reduction strategies and implementation of multimodal analgesia, we sought to determine whether immediate post-surgical opioid consumption was different between THA and TKA. METHODS:A single-institution total joint arthroplasty database was used to identify patients who underwent elective THA and TKA from 2016 to July 2019. Baseline demographic data, operative time (defined by incision time), and American Society of Anesthesiologist (ASA) class were collected. Morphine milligram equivalents (MME) were calculated and derived from prospectively documented nursing opioid administration events, while visual analog scale (VAS) scores represented pain levels, both of which were collected as part of our institution's standard protocols. Activity Measure for Post-Acute Care (AMPAC) was used to determine physical therapy progress. RESULTS:; p < 0.01). THA patients had lower ASA scores in comparison to TKA patients (p < 0.01). Aggregate opioid consumption (93.76 MME vs 147.55 MME; p < 0.01) along with first 24-h and 48-h usage was significantly less for THA as compared to TKA. Similarly, mean pain scores (4.15 vs 5.08; p < 0.01) were lower for THA, while AMPAC mobilization scores were higher (20.88 vs 19.29; p < 0.01) when compared to TKA. CONCLUSION/CONCLUSIONS:THA patients reported lower pain scores and were found to require less opioid medication in the immediate post-surgical period than TKA patients.

INTRODUCTION/BACKGROUND:Spinal anesthesia (SA) is the preferred method of anesthesia at many centers for total joint arthro- plasty (TJA). However, a small subset of patients fails SA, necessitating a conversion to general anesthesia (GA). This report assesses the patient characteristics associated with failed SA. METHODS:A retrospective study was conducted on patients who underwent SA during their primary TJA between Janu- ary 2015 and December 2016 at our institution. A subset of this group required a conversion from SA to GA. Anesthesia reports were reviewed for the number of attempts at SA and the documented reason for failure. The SA failure cohort was then subdivided into failure categories based on the reasons that had been provided. RESULTS:A total of 5,706 patients were included in this study, 78 of which experienced SA failure. The number of attempts was most strongly associated with SA failure, with three attempts resulting in a five times increased failure rate (OR = 4.73, p = 0.010) and four attempts resulting in 12 times increased failure rate compared to the no failure cohort (OR = 12.3, p < 0.001). Greater than two attempts occurred in 87.5% of the "technical failure" sub-group of the SA failure cohort (p < 0.001). No difference was demon- strated among the other patient characteristics, such as age, sex, body mass index, race, American Society of Anesthesia (ASA) score, and surgical time. CONCLUSIONS:The results suggest that the major predic- tor influencing spinal to general anesthesia conversion was the number of attempts at SA, especially among technical failure cases. Based on the results, it may be appropriate for anesthesiologists to convert to GA after two failed spi- nal attempts. Further studies are warranted to assess this relationship for firm clinical recommendations.

The Centers for Medicaid and Medicare Services (CMS) removed primary total knee arthroplasty (TKA) from the inpatient-only list in January 2018. This study aims to compare outcomes in Medicare-aged patients who underwent primary TKA and had an in-hospital stay spanning less than two-midnights to those with a length of stay greater than or equal to two-midnights. We retrospectively reviewed 4,138 patients ages ≥65 who underwent primary TKA from 2016 to 2020. Two cohorts were established based on length of stay (LOS), those with an LOS <2 midnights were labeled outpatient and those with an LOS ≥2 midnights were labeled inpatient as per CMS designation. Demographic, clinical data, knee injury and osteoarthritis outcome score for joint replacement (KOOS, JR), and veterans RAND 12 physical and mental components (VR-12 PCS & MCS) were collected. Demographic differences were assessed with Chi-square and independent sample t-tests. Clinical data and KOOS, JR and VR-12 PCS and MCS scores were compared by using multilinear regression analysis, controlling for demographic differences. There were 841 (20%) patients with a LOS < 2 midnights and 3,297 (80%) patients with a LOS ≥ 2 midnights. Patients with a LOS < 2 midnights were significantly younger (71.70 vs. 73.06; p < 0.001), more likely male (42.1 vs. 25.7%; p < 0.001), Caucasian (68.8 vs. 57.7%; p <0.001), have lower BMI (30.80 vs. 31.92; p < 0.001), Charlson Comorbidity Index (CCI; 4.62 vs. 4.96; p < 0.001), and American Society of Anesthesiologists (ASA) class II or higher (p < 0.001). These patients were more likely to be discharged home compared to patients with LOS ≥ 2 midnights (95.8 vs. 73.1%; p < 0.001). Patients who stayed ≥ 2 midnights reported lower patient-reported outcome scores at all time-periods (preoperatively, 3 months and 1 year), but these differences did not exceed the minimum clinically important difference. Mean improvement preoperatively to 1 year postoperatively in KOOS, JR (22.53 vs. 25.89; p < 0.001), and VR-12 PCS (12.16 vs. 11.49; p = 0.002) was statistically higher for patients who stayed < 2 midnights, though these differences were not clinically significant. All-cause ED visits (p = 0.167), 90-day all-cause readmissions (p = 0.069) and revision (p = 0.277) did not statistically differ between the two cohorts. TKA patients classified as outpatient had similar quality metrics and saw similar clinical improvement following TKA with respect to most patient reported outcome measures, although they were demographically different. Outpatient classification is more likely to be assigned to younger males with higher functional scores, lower BMI, CCI, and ASA class compared with inpatients. This Retrospective Cohort Study shows level III evidence.

PURPOSE/OBJECTIVE:The purpose of the study was to utilize a large-scale biomorphometric computer tomography (CT) database to determine the desirable starting point and angle for placement of the femoral intramedullary rod in the sagittal plane. METHODS:A CT-based modeling and analytics system (SOMA, Stryker, Mahwah, NJ) was used to evaluate 1029 entire-femur CT scans. From this, 19,464 simulations were run to test whether a 20 cm intramedullary rod, with a radius of 4 mm, would successfully pass through the femoral canal before contacting cortical bone. First, modelling included varying angles from 0-6 degrees in the sagittal plane, at 1-degree intervals. Next, the start point was adjusted with an assumed 3 degrees of induced flexion in comparison to the mechanical axis. RESULTS:A total of 5012 simulations were able to place the femoral intramedullary rod 20 cm into the canal. The angle of the rod that created the highest proportion of successful jig placement was at a 3-degree angle of induced flexion to the orthogonal plane of the transepicondylar axis (TEA), with 33.7% successful jig placements. The starting point for the greatest proportion of successful guide placements was 48.5% along the distance between the sTEA, slightly closer to the lateral side. In the AP plane, the average distance to the ideal start point was 12.1 mm anterior to the PCL. CONCLUSION/CONCLUSIONS:By examining over a thousand femoral CT scans, an angle of 3 degrees of induced flexion was identified in the sagittal plane with the highest proportion of successful placement of an intramedullary rod before cortical contact. It is important to note the high rate of failure in completely inserting the 20 mm rod. LEVEL OF EVIDENCE/METHODS:This is a prospective computer based model.

PURPOSE/OBJECTIVE:Total Knee Arthroplasty (TKA) procedures incorporate technology in an attempt to improve outcomes. The Active Robot (ARo) performs a TKA with automated resections of the tibia and femur in efforts to optimize bone cuts. Evaluating the Learning Curve (LC) is essential with a novel tool. The purpose of this study was to assess the associated LC of ARo for TKA. METHODS:A multi-center prospective FDA cohort study was conducted from 2017 to 2018 including 115 patients that underwent ARo. Surgical time of the ARo was defined as Operative time (OT), segmented as surgeon-dependent time (patient preparation and registration) and surgeon-independent time (autonomous bone resection by the ARo). An average LC for all surgeons was computed. Complication rates and patient-reported outcome (PRO) scores were recorded and examined to evaluate for any LC trends in these patient related factors. RESULTS:The OT for the cases 10-12 were significantly quicker than the OT time of cases 1-3 (p < 0.028), at 36.5 ± 7.4 down from 49.1 ± 17 min. CUSUM and confidence interval analysis of the surgeon-dependent time showed different LCs for each surgeon, ranging from 12 to 19 cases. There was no difference in device related complications or PRO scores over the study timeframe. CONCLUSION/CONCLUSIONS:Active Robotic total knee arthroplasty is associated with a short learning curve of 10-20 cases. The learning curve was associated with the surgical time dedicated to the robotic specific portion of the case. There was no learning curve-associated device-related complications, three-dimensional component position, or patient-reported outcome scores. LEVEL OF EVIDENCE/METHODS:Level II.